What are the properties of the Alkali Metals? (5 points)
React vigorously with water
Become more reactive as you go down the group
What are the Halogens?
Fluorine (F), Chlorine (Cl), Bromine(Br), Iodine (I) and Astatine (At).
What are the properties of the Halogens?
darker as you go down the group
reactivity decreases as you go down the group
boiling points increases as you go down the group
What is the Mass of a Proton?
What is the Mass of a Neutron?
What is the Mass of an Electron?
Negligible/ Nearly 0
What is the charge of a Proton?
What is the charge of a Neutron?
What is the charge of an Electron?
Where in an atom would you find Protons?
Where in an atom would you find Neutrons?
Where in an atom would you find Electrons?
Energy shells around the Nucleus
What does AMU stand for ?
Atomic mass unit
What does the Atomic Number show?
The number of protons
What are equal to protons in an atom?
What is the mass Number ? (atomic mass)
mass of nucleus
(protons + neutrons)
How do you work out the number of neutrons?
No. neutrons = mass number - atomic number
Why are atom neutrally charged?
They have an equal amount of protons and electrons
What are isotopes?
Atoms of the same element that have different number of neutrons in their nucleus
True or False the chemical properties of isotopes are different ?
False because they have the same number of electrons
What is the relative atomic mass? (Ar)
The average mass of all isotopes taking into account their relative abundance
abundance - how much
How do you work out the Ar ?
How do you work out the mass of a compound?
Add up the relative atomic mass of each atom
How many electrons in shell ...
What is Ionic Bonding? (explain)
Bonding between a Metal and a Non- metal
The metal loses an electron and the non-metal gains it.
Held together through electrostatic attraction.
What are the properties of an Ionic compound?
Conduct electricity When molten or dissolved in Water
Form an ionic lattice
High melting and boiling points
Hard to separate
can decompose back to their elements
What is covalent bonding?
Bonding between two Non-metals
They share electrons to achieve a noble gas state
Held together by intermolecular forces
What are the properties of a simple covalent structure?
Do not conduct electricity in any state
Low melting and boiling point (even when the force is strong)
Insoluble in water (may dissolve in other liquids)
Liquid or gas at room temperature
What are the properties of a giant covalent structure?
Regular arrangement e.g. a diamond
High melting point
Don't generally conduct electricity
Insoluble in all liquids
What are the properties of a Diamond?
Hardest natural substance known on earth
Shiny / sparkly
very high melting point 3500°c +
held together by strong covalent bonds
each carbon has four bonds
made entirely of carbon
Does not conduct electricity because all the electrons are held together between atoms
What are the properties of Graphite?
Made entirely of carbon
used in pencils
has a layered structure
held together by strong covalent bonds but with weak intermolecular forces allowing them to slide
high melting point
each carbon atom uses three of its bonds
has delocalised electrons as only 3 are used in bonding
can conduct electricity
what are the properties of silicon dioxide?
High melting point
strong covalent bonds
used in sandpaper
each silicon atom makes four bonds to oxygen atoms
What's a thermosetting polymer?
It can only be moulded once as it sets when it comes into contact with heat
What's a thermo softening polymer?
Can be moulded many times as when it comes into contact with heat it melts
Do Polymers have a melting range or point?
Melting range as they are not pure subatances
Why can thermosetting only be moulded once?
They have cross links that hold them in position
What difference makes LDPE and HDPE?
They are made under different conditions and have a different catalyst
What does malleable mean?
Can change shape (soft / flexible)
What does ductile mean?
Can stretch without snapping
what does sonorous mean?
When it is struck it will make a sound
Why do metals conduct electricity well?
They have free moving electrons (delocalised)
What are properties of metal?
have high melting pints
What is metallic bonding?
Bonding between two metals
Atoms become positively charged as the free electrons move away
The sea of electrons mean the atoms are attracted
How do you work out the percentage of an element in a compound?
Atomic mass of the element
atomic mass of compound
then times 100
% of Carbon in CO212/44 x 100 = 27.27 %
What is the empirical formula?
The smallest, whole, number of atoms in a formula
9g of Aluminium reacts with 35.5g of Chlorine
What is the empirical formula?
Ar 27 35.5
Mass/Ar 27/9 = 0.33333...35.5/35.5=1
Instructions for Empirical formula
Draw a table with the number of elements +1 columns
Draw 6 rows Labelled Element, Mass, Ar, Mass/Ar Mole ratio (/ smallest) and Empirical formula
In the rows fill in the information
Make sure the numbers that are created after /smallest are whole numbers
if not times to make the smallest whole number (e.g. 1.5 and 2 times them both by 2 to get 3 and 4)
write your numbers in the correct places after the right element and you have your empirical formula
how to work out the mass that can be made from so much of an element?
What mass of TiO2 can be made from 3.4g of Ti?
Ti + 02 → TiO2
1 mole of .... is
Ti = 48g O2 =32g TiO2 = 80g
For Ti M=W/R = 3.4/48= 0.070833333... mol
For TiO2 We make 0.070833333 mol
W=MxR = 0.07083333... x 80
How much limestone would you need to make 5.6g of quick lime?
CaCO3 → CaO + CO2
=100g 56g 44g
5.6 = 56/10
10g of CaCO3
How much MgO will be made from 2g of Mg?
2Mg + O2 → 2MgO
W=2g M=? R=24
Molar ratio is 1:1 so 0.083333. mol of Mg makes 0.08333... of MgO
W= 0.08333.. x 40 = 3.3333...g
We expected to get 3.333..g of MgO ut we only got 1.65g
What's the percentage yield?
1.65/3.333333... x100 = 49.5%
Percentage yield = actual yield /theoretical yield x100
What is chromatography used for ?
To separate different substances dissolved in a liquid
How is gas Chromatography carried out?
The sample is dissolved in a solvent, then injected into one end of the column.An unreactive gas - usually nitrogen - carries the sample through the column.Different substances in the sample travel through the column at different speeds and so become separated from each other.The separated substances leave the column one after the other. As they leave, they are detected by a detector.
What is the retention time ?
The time taken for a substance to travel through the column
What do the peaks show?
the number of compounds present in the sample
What does the position of each peak show?
the retention time
What does a mass spectrometer do?
A mass spectrometer is able to identify substances very quickly and accurately. It can detect very small amounts
what is a GC-MS?
this combined GC-MS method allows the separated substances leaving the column of the GC machine to be detected.
mass spectrometry -higher
The mass spectrometer can be used to identify substances quickly and accurately, and in very small amounts. It can also provide the relative formula mass of the substances separated by gas chromatography. The peak furthest to the right in a mass spectrum is called the 'molecular ion peak'. Its relative mass is the relative formula mass of the substance being analysed.